PHP unidentified index: gender söyleyerek tutar? Ben hata nerede emin değilim.

HTML:

<label>Gender:</label> <input type="radio" name="gender" value="1">Male <input type="radio" name="gender" value="0">Female

JQuery:

gender: $("input[@name=gender]:checked").val()

PHP:

$gender = $_POST['gender'];
if($gender == '') {
  echo 'Please select gender';
}